Optical recorder

ABSTRACT

Optical information generating system for use in display or recording apparatus. The system is characterized by a rotatable character mask in the shape of a drum which has a plurality of character fonts alternately disposed along the longitudinal axis thereof. The drum is displacable along its longitudinal axis so that each font can be independently moved into cooperative relationship with a source of illumination.

United States Patent Chen [is] 3,685,406 1 51 Aug. 22, 1972 [54] OPTICAL RECORDER [72] Inventor: Philip L. Chen, Penfield, NY.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

22 Filed: Dee.2l, 1970 21 Appl.No.: 99,940

[52] US. Cl. ..95/4.5 R, 178/30, 340/324 R [51] Int. Cl ..B41b 17/10, B4lb l7/00 [58] Field of Search... ....95/4.5 R; 178/67 R, 15,30; 340/324 R [56] References Cited UNITED STATES PATENTS 3,303,764 2/1967 Kudlicki et a1 ..95/4.5 R

2,475,497 7/1949 l-larrold et a1 ..95/4.5 R

2,726,940 12/1955 Buhler ,.95/4.5 X

3,400,387 9/1968 Appleton ..340/324 x 3,344,722 10/1967 Cunningwell ..9s/4.s R 3,252,392 5/1966 Ward ..95/4.s R 3,336,849 8/1967 Broglio ..95/4.5 R

Primary ExaminerSamuel S. Matthews Assistant Examiner-Robert P. Greiner Attorney-James J. Ralabate, John E. Beck and Benjamin B. Sklar [57] ABSTRACT Optical information generating system for use in dis play or recording apparatus The system is characterized by a rotatable character mask in the shape of a drum which has a plurality of character fonts alternately disposed along the longitudinal axis thereof. The drum is displacable along its longitudinal axis so that each font can be independently moved into cooperative relationship with a source of illumination.

11 Claims, 13 Drawing Figures PATENTED M1822 I972 SHEEY 1 0F 9 INVENTORQ PHILIP L. CHEN PATENTED M1922 I972 SHEET 3 [IF 9 PATENTED AUG 22 I972 SHEEI 5 [IF 9 PATENTED M1922 m2 sum 6 OF 9 PATENTED AUG22 1972 SHEET 7 BF 9 OPTICAL RECORDER BACKGROUND OF THE INVENTION This invention relates, in general, to an optical character generating system and, more particularly, to recording apparatus employing an optical character generating system.

Optical character generators of the type employed in automatic display and recording apparatus usually comprise a character mask in the shape of a disc or drum. The characters may be either opaque with a transparent background or vice-versa. In either case, illumination from a stationary light source is directed through the mask to thereby form images of information carried on the mask. Where the apparatus is a recorder, the images are presented to a photosensitive recording medium to thereby form images thereon.

The characters are disposed on the disc or drum as a set or sets of characters. A set of characters or fonts may comprise any combination of alphanumeric symbols, for example, capital letters of the alphabet followed by small letters of the alphabet. The set or sets may also comprise only capital letters or capital letters followed by the digits -9.

As the drum or disc is moved past the stationary. light sources, which are selectively flashable in accordance with information to be generated, the light sources are flashed when the particular characters to be generate move in front of the light source.

It is highly desirable that apparatus of the type herein contemplated have the capability of generating information in a plurality of languages or in the same language but in different character fonts. One method of accomplishing the foregoing would be to provide individual masks each having a different language or different fonts of the same language. The individual masks would be interchangeable one with the other. However, as will be appreciated, such an arrangement is undesirable both from a standpoint of fabrication and operator convenience. With respect to the former it would be necessary to manufacture many different masks resulting in increased costs and storage problems and with respect to the latter, it would require changeover to a new mask each time a different language or font is to be used. The gravity of the operator inconvenience will be appreciated from a consideration of a printing job comprising numerous pages each of which would require a different mask. In such a situation it would be necessary to change masks each time a page of that job was to be printed.

Accordingly, the general object of this invention is to provide a new and improved optical character generating system.

It is a more particular object of this invention to provide a new and improved optical character generating system for use in recording apparatus.

Another object of this invention is to provide an optical character generating system having multiple font capability.

BRIEF DESCRIPTION OF THE DISCLOSURE Briefly, the above-cited objects are accomplished by the provision of a rotatably mounted character mask shaped in the form of a drum or cylinder. A plurality of character fonts are alternately disposed along the longitudinal axis of the drum.

A plurality of selectively fiashable light sources are stationarily mounted such that they cooperate with only one font at a time. The character mask or drum is shiftably mounted with respect to the light sources so as to be able to move any one of the fonts into cooperative relationship with the light sources.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a schematic view of printing apparatus representing the invention;

FIG. 2 is a schematic perspective view of an optical character mask and optical projection system forming a part of the apparatus illustrated in FIG. 1;

FIG. 3 is a block diagram depicting the cycle of operation for generating optical characters by means of the mask and projection system of FIG. 2;

FIG. 4 is an expanded view of the character mask illustrated in FIG. 2;

FIG. 5 is an expanded view of a character mask utilized for the purpose of providing a better understanding of the invention;

FIGS. 6 and 7 are schematic perspective views of the character drum of FIG. 5 illustrating the projection of the characters thereof onto a photoconductive surface;

FIGS. 8-10 are similar to FIGS. 5-7, but illustrate a timing slit arrangement and its effect on the projection of characters onto the photoconductive surface;

FIG. 11 is an enlarged schematic perspective view of the optical system forming a part of the invention;

FIG. 12 is an expanded view of a modified character mask; and

FIG. 13 is a schematic plan view of the character mask of FIG. 12 and structure for shiftably mounting same.

DETAILED DESCRIPTION OF THE INVENTION General As shown schematically in FIG. 1 the automatic xerographic reproducing apparatus comprises a xerographic plate 20 including a photoconductive layer or light-receiving surface on a conductive backing and formed in the shape of a drum, which is mounted on a shaft journalled in a frame to rotate in the direction indicated by the arrow to cause the drum surface sequentially to pass a plurality of xerographic processing statrons.

For the purpose of the present disclosure, the several xerographic processing stations in the path of movement of the drum surface may be described functionally, as follows:

A charging station, at which a uniform electrostatic charge is deposited on the photoconductive layer of the xerographic drum;

An exposure station, at which a light or radiation pattern of copy to be reproduced is projected onto the drum surface to dissipate the drum charge in the exposed areas thereof and thereby form a latent electrostatic image of the copy to be reproduced;

A developing station, at which a xerographic developing material including toner particles having an electrostatic charge opposite to that of the electrostatic latent image are cascaded over the drum surface, whereby the toner particles adhere to the electrostatic latent image to form a xerographic powdered image in the configuration of the copy being reproduced;

A transfer station, at which the xerographic powder image is electrostatically transferred from the drum surface to a transfer material or support surface; and,

A drum cleaning and discharge station, at which the drum surface is brushed to remove residual toner particles remaining thereon after image transfer, and at which the drum surface is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon.

The charging station is preferably located, as indicated by reference character A. As shown, the charging arrangement includes a corona charging device 21 which includes a corona discharge array of one or more corona discharge electrodes that extend transversely across the drum surface and are energized from a high potential source and are substantially closed within a shielding member.

Next subsequent thereto in the path of motion of the xerographic drum is an exposure station B. A flash expose optical projection system is provided to project an image onto the surface of the photoconductive drum from a rotating character drum 22.

The optical projection system comprises a stationary lens and prism structure generally indicated 23 comprising a plurality of prisms arranged to reflect light, emanating from a plurality of directions, in one direction through a character mask in the shape of a drum 24. The lamps associated with the prisms and character mask are adapted to be flashed in accordance with output from a digital computer, in such a manner as to enable printing of a line-at-a-time on the character drum.

Adjacent to the exposure station is a developing station C in which there is positioned a developer apparatus 30 including a casing or housing having a lower or sump portion for accumulating developer material. A bucket type conveyor is used to carry the developing material to the upper part of the developer housing where it is cascaded over a hopper chute onto the xerographic drum to effect development. A toner dispenser 35 is used to accurately meter toner to the developing material as toner particles are consumed during the developing operation.

Positioned next and adjacent to the developing station is the image transfer station D which includes a sheet feeding arrangement adapted to feed sheets of support material, such as paper or the like, successively to the xerographic drum in coordination with the presentation of the developed image on the drum surface at the transfer station.

The sheet feeding mechanism includes a sheet feed device 40 adapted by means of vacuum feeders to feed the top sheet of a stack of sheets on a tray 41, to rollers 42 cooperating with the belts of paper transport 44 for advancing the sheet sufficiently to be held by paper transport 44 which in turn, conveys the sheet to a sheet registration device 45 positioned adjacent to the xerographic drum. The sheet registration device arrests and aligns each individual sheet of material and then in timed relation to the movement of the xerographic drum, advances the sheet material into contact with the xerographic drum in registration with a previously formed xerographic powder image on the drum.

The transfer of the xerographic powder image from the drum surface to the sheets of support material is effected by means of a corona transfer device 51 that is located at or immediately after the line of contact between the support material and the rotating drum. In operation, the electrostatic field created by the corona transfer device is effective to tack the support material electrostatically to the drum surface, whereby the support material moves synchronously with the drum while in contact therewith. Simultaneously with the tacking action, the electrostatic field is effective to attract the toner particles comprising the xerographic powder image from the drum surface and cause them to adhere electrostatically to the surface of the support material.

Immediately subsequent to the image transfer station there is positioned a stripping apparatus of paper pickoff mechanism 52 for removing the sheets of support material from the drum surface. This device, includes a plurality of small diameter orifices supplied with pressurized aeroform fluid by a suitable pulsator or other device. The pulsator is adapted to force jets of pressurized aeroform fluid through the outlet orifices into contact with the surface of the xerographic drum slightly in advance of the sheet of support material to strip the leading edge of the sheet from the drum surface and to direct it onto an endless conveyor 55 whereby the sheet material is carried to a fixing device 60. At the fixing device, the transferred xerographic powder image onthe sheet of support material is permanently fixed or fused thereto as by heat. After fusing, the reproduction is discharged from the apparatus at a suitable point for collection externally of the apparatus by means of the conveyor 65. In the embodiment shown, the reproductions are discharged from conveyor 65 into a receiving tray 61.

The next and final station in the device is a drum cleaning station E, having positioned therein a corona preclean device 66, a drum cleaning device adapted to remove any powder remaining on the xerographic drum after transfer by means of a rotating brush 71, and a discharge lamp LMP-l adapted to flood the xerographic drum with light to cause dissipation of any residual electrical charge remaining on the xerographic drum.

To remove residual powder from the xerographic drum, there is disposed a cylindrical brush 71 rotatably mounted on an axle and driven by a motor, not shown. For collecting powder particles removed from the xerographic drum by the brush, there is provided a dust hood 73 that is formed to encompass approximately two-thirds of the brush area. To ensure thorough cleaning of the brush, a flicking bar 74 is secured to the interior of the dust hood adjacentthe edge of the outlet duct 75 of the dust hood and in interfering relation with the ends of the brush bristles whereby dust particles may be dislodged therefrom.

For removing dust particles from the brush and dust hood, an exhaust duct 76 is arranged to cover the outlet of the dust hood, the exhaust duct being connected at its other end to the wall of a filter box 77 attached to the dust hood. A filter bag 78 is secured within the filter box, with the mouth of the filter bag in communication with exhaust duct. Motor fan unit MOT-5 and MOT-6, connected to the filter box, produces a flow of air through the filter box drawing air through the area surrounding the xerographic drum and the dust hood, the air entraining powder particles removed from the drum by the brush as the air flows through the dust hood.

Powder particles are separated from the air as it flows through the filter bag so that only clean air reaches the motor unit.

Suitable drive means are provided to drive the drum, rotating mirror and sheet feed mechanism at predetermined speeds relative to each other, and to effect operation of the bucket-type conveyor and toner dispenser mechanism and the other operating mechanisms.

The character mask or drum 24 forms a part of an optical projection system comprising the lens and prism structure 23, to be discussed in detail hereinafter, and a plurality of flash lamps 100. v

The flash lamps 100 are flashable in accordance with information derived from a computer, the illumination therefrom being directed by means of the lens and prism structure 23 through transparent characters of the character mask 24. The characters so formed produce latent electrostatic images of alphanumeric characters on the photoconductive plate 20.

Each of the character spaces occupied by a transparent character on the xerographic plate is associated with a transparent slit or aperture 102, the slits being disposed about the circumference of the drum. A slit sensor 104 disposed adjacent the outer surface of the drum intercepts a light from a light source 106 each time a slit 102 passes between the sensor and the light source. Pulses generated by the sensor 104 are utilized, as will be discussed hereinafter, to effect firing of the lamps 100.

The block diagram of FIG. 3 illustrates, in general, the cycle of operation for firing of the flash lamps in accordance with the output from a computer 104 which is utilized as a buffer storage device containing sufficient data to print a complete page of 60-66 lines. A model DDP 516 computer manufactured by Computer Controls Company has been satisfactorily employed for this purpose.

Initially only a portion of the data contained in the buffer device 108 is written into a memory device 110 which may comprise a pair of PT 40 fast access memory cards having a capacity of 16 two-character words at 16 bits per word. Such cards are manufactured by Xerox Data Systems. Writing into memory is accomplished by means of a process control shift re gister 112 driven by a 5 MHz clock. The shift register also controls the reading of the data into a comparator 114 which may comprise suitable logic components, for example, AND gates (not shown) for deriving outputs when positive comparisons are made. The other input to the AND gates may be derived from a counter 116.

The counter 116 is preset to a code representing the first character on the character drum 24. Accordingly, when the first or initial portion of data is read into the comparator 110 it is compared to the code representing the aforementioned first character or in other words the preset value of the counter. Each successive character on the character drum is represented by a code in the counter on incrementing thereof. This incrementing of the counter is accomplished by virtue of the pulses from the slit sensor 104. It can be seen that the code representing the second character on the drum will be represented by the preset value of the counter plus 1.

When the code in the comparator 114 is the same as the code from the memory 110, a latch 118, which may comprise a flip-flop (not shown) is set. Pulses from the sensor 104 are ANDed with the outputs from the latches to thereby actuate lamp firing circuits 120.

In accordance with the objects of the present invention, the character mask or drum 24, as illustrated in FIG. 4, comprises columns 124 of transparent characters disposed on the periphery thereof in groups of four columns. In the preferred embodiment of the invention 30-33 such groups of four columns each, are disposed along the longitudinal axis of the drum, each group being spaced from adjacent groups by at least a distance equal to the width of one group of columns. The circumferential extent of one group of columns is such that each column of a group occupies a different quadrant of the drum. This produces a staggered arrangement of the columns or character sets which permits utilization of one flash lamp for each group of four columns. Where the columns are not staggered but are disposed in a side by side array, a lamp is required for each column.

Since the columns 124 are staggered, each flash lamp is fired four times for each revolution of the character drum. Accordingly, during one revolution, data corresponding to the first column of each group is put into the comparator 114 and compared against the code in the counter 1 16. Since one fourth of the data in the buffer is handled at one time, this quantity of data may be thought of as one quadrant of data.

For each column of information from the memory that contains an A, a corresponding latch 118 is set. Subsequent thereto, when the slit 102 associated with the character space for the A is sensed by the sensor 104, the lamp firing circuits 120 corresponding to the latches previously set are triggered. Simultaneously, the pulse from the sensor 104 increments the counter 116 by one. The code for the letter B is now placed in the comparator with subsequent comparison to the first quadrant of data from the buffer. Each character of the first column is compared in the foregoing manner to the first quadrant of data.

At the end of each column 124 adjacent the last character space of that column there is provided a transparent slit which effects pulsing of a photodetector 132, the pulse from which conditions the register 112 for writing the second quadrant of data from the buffer into memory with subsequent reading from memory into the comparator. The second quadrant of data is read into the comparator, as before, for each character of the second column which, each character of the second column being placed one at a time into the comparator. The sequence of operation for the third or fourth quadrants of data from the buffer is the same as described above.

As can be seen from FIG. 4, the slits 102 do not occupy the same relative position with respect to their associated character spaces. In other words the slit associated with the first letter of any first column is disposed adjacent the trailing edge, assuming that the character mask of FIG. 4 is moving upwardly past a flash exposure station, of the first character space. The slit associated with the last character of the group is adjacent the leading edge of that character space.

The purpose of the specific arrangement of the slits 102 will be better understood by first considering the operation of a character mask on which the slits are spaced the same, relative to each character space i. e., adjacent the trailing edge of the space. To this end, reference may be had to FIGS. 5, 6, and 7 wherein there is disclosed an expanded view (FIG. of a character mask or drum 140 having a plurality of columns 142 of transparent characters disposed thereon in a side by side relationship. The character drum is adapted for rotation in the counterclockwise direction while a photosensitive insulating plate 144 optically aligned therewith is adapted for rotation in the clockwise direction.

Each column 142 of characters, herein illustrated as the capital letters of the alphabet, represents a character set which extends over the entire circumference of the character drum. In the present embodiment it is desired to print a complete line of characters on the photoconductive plate 144 which line comprises one character from each column of the character drum. Accordingly, flash lamps, not shown, associated, one with each column, will flash once for each revolution of the character drum. Meanwhile, the photoconductive plate rotates the equivalent of one character space. A column of timing slits, one for each character of a column, generally indicated by reference character 146, is sensed to thereby cooperate with an output from a computer to cause flashing of the lamps in accordance with the characters to be recorded. In this particular embodiment each timing slit occupies the same position relative to the character space associated with a particulate character, as all other slits. In other words, each timing slit is in line with the trailing edge of the character space occupied by the character as? sociated therewith.

As shown in FIG. 5, the character A from the first column from the left, is projected onto the photoconductive plate in the position shown, which position lies below a stationary reference line 148 used herein for illustration purposes only. Assuming that the Z of the fourth column is to be projected onto the plate, it will be seen that because the photoconductive plate has moved clockwise a full line or character space the Z is projected onto the drum, not on the same line space as the A but one line space below. This is due to the fact that with such a timing slit arrangement all characters are projected below the reference line and'by the time the Z moves through the optical axis the line space on the drum containing the A has moved above the reference line.

In order to obviate this problem a plurality of differently spaced timing slits 150, one for each character set is provided adjacent the right edge of a character drum 152. (See FIGS. 810). These slits or indicia may be apertures" in the character drum or transparent windows in an opaque mask. Either of the foregoing may be employed, the essential requirement being the capability of passing light from the light source 106 to the light sensor 104 which may be a photodiode. The sensor and light source are in line with the optical axis extending between the two drums.

The slits or windows, as shown in FIG. 8 are arranged relative to columns 154 of character such that the one associated with the A is substantially in line with the trailing edge of the character space occupied by the A and the one associated with the character space occupied by the Z is substantially in line with the leading edge of the character space occupied by the Z. The slits or windows intermediate the ones associated with the A and Z are incrementally progressed such that the one associated with the M is substantially in line with the middle of the character space occupied thereby. It can be seen from FIG. 8 that when the slit associated with the A (first column from left) passes the light sensor 104, the A is projected onto a plate 156 in an area that lies below an reference line 158. From FIG. 10, it can be seen that when the slit associated with the Z (fourth column from left) passes the light sensor, the Z on the drum is in a position so as to be projected onto the plate in a position above the reference line, which position due to the clockwise rotation of the plate is in line with the position of the A.

In the preferred embodiment of the character mask, columns 124, as shown in FIG. 4, are placed on a character drum 24 in groups of four, the drum being sufficiently long (i. e. 9.9 inches) to place 33 such groups thereon with a space between groups equal to at least the distance across the columns in any one group. As shown the columns of each group are staggered such that the columns in one group, beginning with the first character of the first column or set from the left, and ending with the last character of the fourth column or set, extend substantially the circumference of the drum. As in the case of embodiment of FIGS. 5-7, it is intended that a line comprising a character from each column or set be printedfor each revolution of the drum.

. Since the columns of one group, in the embodiment shown, occupy only one fourth of the circumferential extent or one quadrant of the drum, four characters from each group must be projected onto the same line of a photoconductor plate 20 for each revolution of the character drum 24. Expressed another way, a character from each column in a group must be projected for every one-fourths revolution of the character drum. During this quarter revolution the line space on the photoconductive plate moves one fourth its total distance. This means that for the characters for any two adjacent columns to be projected onto the same line space of the plate, the timing slits 102 associated with those two characters should be approximately one fourth the total distance between the first and last timing slits of one group. To this end the character drum 24 is, as shown in FIG. 4, the first one of timing slits 102 is in line with the trailing edge of the character space associated with the A and the last timing slit of fourth column of the first group is in line with the leading edge of the character space associated with the last Z in that group. It will be seen upon further examination that the timing slit associated with the character space associated with the Z of second column of the same group occupies a space in line with the middle of the Z.

While the number of columns in each group is illustrated as being four, this need not be the case. Any number of convenient columns may be employed depending on the particular application and the end result desired.

By referring to FIG. 4 and bearing in mind the discussion relative to FIGS. 57, it can be seen that for each group of columns, an A by way of example, can be projected onto and along the same line on the plate 130 for each column position of the character drum. Projection of characters commences when the timing slit associated with the first A of the first column is sensed by the light sensor. At this time the first A is projected onto the plate which then rotates clockwise one fourth of a line space while the character drum rotates approximately a quarter of a revolution. Now the timing slit for the second A is sensed by the light sensor. It will be apparent that the differential spacing of these two timing slits relative to their respective As causes the second A to be projected onto the photoconductive plate a distance one fourth of a line space higher than the preceding A thereby placing the second A on exactly the same line on the plate as the first A. With respect to the third A, it will be seen that its timing slit (see FIG. 9) will have the effect of causing the third A to be projected one half of a line space higher on the plate thereby placing it on the same line with the first two characters. Simultaneously, the projection of other first, second and third As of the other groups has taken place along the same line of the plate.

While the slit sensor is disposed adjacent the exposure station, it will be appreciated that it may-occupy other locations if the machine configuration so warrants. For example, the slit sensor may be displaced 90 from the optical axis, in which case, the timing slits would also be displaced an equal amount and would occupy their same spacing relative to each other.

The lens and prism structure 23, as best shown in FIGS. 1 and 11, comprises a prism structure 160 which may be fabricated as a single piece or may be assembled from individual prism elements 162 and blocks 163. A plurality of strip condensers 164 comprising individual condenser elements 166 cooperate with condenser elements 167 molded on the strip prism to collimate the illumination from the lens 100 for transmission to the prism elements 162.

The lamps 100 of which there are thirty-three in the preferred embodiment are arranged in three rows to form an arc of approximately 270 about the top, bottom and rear sides of the strip prism structure 160. The rows of lamps are offset to each other, the top row being offset to the right side of the back row, as viewed from the left in FIG. 11, while the bottom row is offset to the left side of the top row. The amount of offsetting in each of the foregoing cases is equal to four column widths. The collimated light from each lamp in the top and bottom rows is reflected 90 by the strip prism structure in the forward direction toward the character mask 24.

The light output from the back row of the lamps travels straight through the blocks 163 which are disposed intermediate a pair of prism elements 162.

The illuminated characters are magnified 2-3 times and are projected onto the photoconductive drum by means of a strip lens 170. One element (i. e. one individual lens) of the strip lens covers or images four characters on the drum. As shown, these reduced size character columns are grouped on the character drum leaving the aforementioned spaces between groups, hence, the character groups are readily baffled by means of a bafi'le structure 172 to thereby prevent optical cross-talk between strip lens elements.

The aforementioned inter-group spacing on the drum lends itself to carrying out the objects of the present invention by the provision of a modified character mask 180, illustrated in FIG. 12. The mask 180 is similar to the mask 24 in that the groups of columns are circumferentially staggered, however, unlike the mask 24, it has a plurality of character fonts 182, 184 and 186 each of which is sub-divided into groups of four columns. The subdivisions are altemately disposed along the longitudinal axis (horizontal axis in FIG. 12) of the character mask. The fonts 184 and 186 occupy the otherwise dead space intermediate the groups of what would normally constitute a single font character mask such as mask 24. The fonts are illustrated for sake of convenience, as capital letters of the same alphabet, however, in accordance with the invention, the fonts are intended to be different from one another. For example, the font 182 could be the English alphabet while the fonts 184 and 186 could be letters of other alphabets, commercial symbols or other suitable indicia.

As shown in FIG; 13, the mask 180 is affixed to a drum structure 187 supported by its shafts 188 for rotation in a pair of bearings 189 (only one shown) which in turn are carried by a pair of support members 190 (only one shown) which may be attached in a suitable manner to the supporting frame of the apparatus shown in FIG. 1. The position of the outer races of the bearings 189 may be fixed relative to the shafts 188 by retainers, not shown. The drum structure 187 is held in its operative position by means of fasteners herein illustrated as screws, 192, the ends of which are received in grooves 194 provided in the bearings 189. The orientation of the grooves is such as to allow relative movement between the screws and hearings to thereby allow axial shifting of the drum structure so as to position one of the fonts 182, 184 or 186 in alignment with a stationary light source, not shown, which is disposed within the drum structure. To this end, a plurality of circumferential notches 196, 198 and 200 may be provided for registration with the inner edge 202 of the support member 190.

The illumination transmitted through the character mask passes through a field stop 204 and is suitably baffled by a structure 206. Strip projection lenses 208 magnify the light images and focus them on a photosensitive surface in the case where the optical character generator is employed in a recording device. Motive power for rotating the drum structure past the light source is provided by a motor 210 and suitable drive couplings between the motor and the shaft of the drum structure. The coupling between the motor and the shaft may be such as to allow axial movement of the drum structure without movement of the motor,

It will be understood that various changes in the details, materials, steps and arrangement of parts which have been herein described and illustrated in order to explain the nature of the invention may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. However, while the invention has been described with reference to the structure disclosed herein, it is not intended that the invention be confined to the details as set forth, this application is intended to cover such modifications or changes as may come within the scope of the following claims. For example, shifting the drum structure 180 could automatically be accomplished by means of suitable solenoids and biasing apparatus. Such shifting would be possible without having to enter the machine or apparatus.

What is claimed is:

l. A character generating system comprising:

a rotatable character member containing a plurality of character fonts each of said fonts being divided into a plurality of groups of characters and the groups of characters of one font being alternately positioned with groups of characters of at least one other font along an axis of said character mask;

a plurality of flash lamps equal in quantity to the number of groups in any one font, and

means for varying the relative position of said flash lamps and said character fonts whereby only the characters of one group are illuminated.

2. Structure as specified in claim 1 wherein, said means for varying the relative position of said flash lamps and said character fonts comprises means for shifting the position of said character member.

3. Structure as specified in claim 2 wherein, said means for shifting said character member effects shifting thereof along its longitudinal axis.

4. Structure as specified in claim 3 including,

indicia associated with each character in such a manner as to uniquely define each character;

means for moving said photoreceptive record medium in synchronism with said character member, and

means for sensing said indicia in such a manner as to effect rectilinear placement of characters on said record medium.

5. Structure as specified in claim 1 wherein,

said character member comprises a drum,

said means for varying the relative position between said flash lamps and said character fonts comprises means for shifting said drum member in the direction of its longitudinal extent.

6. Recording apparatus comprising:

a rotatable character mask having a plurality of character fonts each of said fonts being divided into a plurality of groups of characters and the groups of characters of one font being alternately positioned with groups of characters of at least one other font along an axis of said character mask;

means for illuminating one of said fonts;

means for collimating illumination passing through said one of said fonts and focusing magnified images of characters thereof on a photoreceptive recording medium;

a photoreceptive recording medium for receiving said focused images; and 7 means for varying the relative position of said illuminating means and said character mask whereby all groups of characters of one font can be illuminated independently of the groups of characters of said at least one other font 7. Apparatus according to claim 6 wherein,

said character mask comprises a drum member having said character fonts alternately spaced along the longitudinal axis thereof, and

said means for varying the relative position between said il uminatin ea d s id character ma k compr ises mean s f r slil ft iiig sa id drum member in the direction of its longitudinal axis.

8. Apparatus according to claim 6 wherein, said character mask comprises a drum member and wherein said illuminating means comprises one flash lamp for each group of each font.

9. Apparatus according to claim 8 wherein, said means for varying the relative position of said illuminating means and said character mask comprises means for shifting the position of said drum member.

10. Apparatus as set forth in claim 9 wherein, said means for shifting said drum effects shifting thereof along its longitudinal axis.

1 1. Apparatus as set forth in claim 10 including,

indicia associated with each character in such a manner as to uniquely define said each character; means for moving said photoreceptive record medium in synchronism with said character mask, and means for sensing said indicia in such a manner as to effect rectilinear placement of characters on said record medium. 

1. A character generating system comprising: a rotatable character member containing a plurality of character fonts each of said fonts being divided into a plurality of groups of characters and the groups of characters of one font being alternately positioned with groups of characters of at least one other font along an axis of said character mask; a plurality of flash lamps equal in quantity to the number of groups in any one font, and means for varying the relative position of said flash lamps and said character fonts whereby only the characters of one group are illuminated.
 2. Structure as specified in claim 1 wherein, said means for varying the relative position of said flash lamps and said character fonts comprises means for shifting the position of said character member.
 3. Structure as specified in claim 2 wherein, said means for shifting said character member effects shifting thereof along its longitudinal axis.
 4. Structure as specified in claim 3 including, indicia associated with each character in such a manner as to uniquely define each character; means for moving said photoreceptive record medium in synchronism with said character member, and means for sensing saiD indicia in such a manner as to effect rectilinear placement of characters on said record medium.
 5. Structure as specified in claim 1 wherein, said character member comprises a drum, said means for varying the relative position between said flash lamps and said character fonts comprises means for shifting said drum member in the direction of its longitudinal extent.
 6. Recording apparatus comprising: a rotatable character mask having a plurality of character fonts each of said fonts being divided into a plurality of groups of characters and the groups of characters of one font being alternately positioned with groups of characters of at least one other font along an axis of said character mask; means for illuminating one of said fonts; means for collimating illumination passing through said one of said fonts and focusing magnified images of characters thereof on a photoreceptive recording medium; a photoreceptive recording medium for receiving said focused images; and means for varying the relative position of said illuminating means and said character mask whereby all groups of characters of one font can be illuminated independently of the groups of characters of said at least one other font
 7. Apparatus according to claim 6 wherein, said character mask comprises a drum member having said character fonts alternately spaced along the longitudinal axis thereof, and said means for varying the relative position between said illuminating means and said character mask comprises means for shifting said drum member in the direction of its longitudinal axis.
 8. Apparatus according to claim 6 wherein, said character mask comprises a drum member and wherein said illuminating means comprises one flash lamp for each group of each font.
 9. Apparatus according to claim 8 wherein, said means for varying the relative position of said illuminating means and said character mask comprises means for shifting the position of said drum member.
 10. Apparatus as set forth in claim 9 wherein, said means for shifting said drum effects shifting thereof along its longitudinal axis.
 11. Apparatus as set forth in claim 10 including, indicia associated with each character in such a manner as to uniquely define said each character; means for moving said photoreceptive record medium in synchronism with said character mask, and means for sensing said indicia in such a manner as to effect rectilinear placement of characters on said record medium. 